Camera module

ABSTRACT

One embodiment of a camera module includes: a lens barrel provided with at least one lens; and a lens holder having the lens barrel coupled thereto, wherein the lens barrel may have a first adhesive part formed thereon having the bottom surface thereof facing the top surface of the lens holder and adhered to the lens holder, the lens holder may have a second adhesive part formed thereon having the top surface thereof facing the bottom surface of the lens barrel and adhered to the lens barrel, and a first recessed groove having at least a portion of an adhesive deposited therein may be formed in the second adhesive part.

TECHNICAL FIELD

Embodiments relate to a camera module.

BACKGROUND ART

The disclosure described in this part merely provides backgroundinformation related to embodiments, and does not constitute the relatedart.

A camera module may be mounted in a CCTV, a vehicle, or the like. Inrecent years, a CCTV has been connected online to enable viewing of animage photographed by the CCTV even at a remote distance. In addition,the quality of an image photographed by the CCTV is also steadilyimproving.

Various types of camera modules may be mounted in a vehicle. Forexample, a camera module, which is capable of securing a rear view whenparking a vehicle, may be mounted on the rear portion of the vehicle.

In addition, a camera module may also be used in a vehicle black box,which has recently been very useful in tracking causes and details ofaccidents, and the like when traffic accidents occur. In addition, thereis a growing trend of using a camera module as a recognition device forclearly and easily grasping the situation in a blind spot, which isdifficult for a vehicle driver or occupant to view directly.

In recent years, the production of a so-called smart car, that is, avehicle equipped with a collision warning system, which detects thepossibility of a collision at the front or rear of the vehicle inadvance while the vehicle is traveling in order to prepare for such acollision, a collision avoidance system, which enables a control devicemounted on the vehicle to directly avoid a collision between vehiclesdriven by these control devices without requiring the driver'soperation, and the like is increasing, and the development of relatedtechnologies is increasing.

The use of a camera module as an external situation recognition deviceof such a smart car is increasing, and accordingly, the production andtechnical development of a vehicle camera module are also increasing.

A camera module may be assembled by coupling a lens barrel having a lensto a lens holder. Here, the lens barrel has the risk of causing damageto elements inside the camera module due to the overflow of an adhesiveor the like in the process of coupling the lens holder and the lensbarrel to each other. Therefore, a solution therefor is required.

When the camera module is assembled by coupling the lens barrel havingthe lens to the lens holder, the lens barrel may be disposed outside adesignated position on the lens holder, and the allowable error rangethereof, in the assembly process. In this case in particular, the focallength between the lens and an image sensor mounted in the camera modulemay differ from a designed value.

Therefore, there is a demand for a structure that is capable ofpreventing the lens barrel from deviating from the designed positionthereof and the error range thereof when the lens barrel is assembledwith the lens holder.

Technical Object

Therefore, embodiments relate to a camera module, which may prevent orremarkably reduce damage to elements inside the camera module due to theoverflow of an adhesive or the like in the process of coupling a lensbarrel to a lens holder.

Further, embodiments relate to a camera module, which has a structurecapable of preventing a lens barrel from deviating from the designedposition thereof and the error range thereof when the lens barrel and alens holder are assembled with each other.

The technical objects to be accomplished by the embodiments are notlimited to the aforementioned technical object, and other unmentionedtechnical objects will be clearly understood from the followingdescription by those having ordinary skill in the art.

Technical Solution

One embodiment of a camera module includes a lens barrel comprising atleast one lens, and a lens holder coupled to the lens barrel, whereinthe lens barrel is formed with a first adhesive portion comprising abottom surface facing a top surface of the lens holder and attached tothe lens holder, and the lens holder is formed with a second adhesiveportion comprising a top surface facing a bottom surface of the lensbarrel and attached to the lens barrel, and wherein the second adhesiveportion is formed with a first recess, to which at least a portion of anadhesive is applied.

Another embodiment of a camera module includes a lens barrel comprisingat least one lens and formed with a first screw-thread in a portion ofan outer circumference thereof, and a lens holder formed with athrough-hole and also formed in an inner circumference of thethrough-hole with a second screw-thread configured to be screwed to thefirst screw-thread, wherein the lens barrel and the lens holder areattached to each other by an adhesive disposed in a gap between thefirst screw-thread and the second screw-thread, the adhesive containinga filler.

A further embodiment of a camera module includes a lens barrelcomprising at least one lens, and a lens holder coupled to the lensbarrel, wherein the lens barrel is formed with a first adhesive portioncomprising a bottom surface facing a top surface of the lens holder andattached to the lens holder, and the lens holder is formed with a secondadhesive portion comprising a top surface facing a bottom surface of thelens barrel and attached to the lens barrel, and wherein the secondadhesive portion is formed thereon with a first protrusion, and thefirst protrusion protrudes in a first direction.

Advantageous Effects

In the embodiments, by preventing an adhesive from flowing into a lensholder and an accommodating unit using a first protrusion, it ispossible to prevent contamination of a printed circuit board, variouselements, and an image sensor provided in the accommodating unit.Thereby, it is possible to prevent or remarkably reduce deterioration inthe performance of a camera module due to contamination.

In addition, in the embodiments, a second adhesive portion is formedsuch that the height of the outer surface thereof is lower than theheight of the inner surface, and an adhesive flows from the innersurface to the outer surface of the second adhesive portion. Thereby, itis possible to prevent the adhesive from overflowing to the innercircumference of the second adhesive portion.

In the embodiments, a lens barrel is attached to the lens holder usingan adhesive containing a filler. Thereby, it is possible to remarkablyreduce the magnitude of displacement by which the lens barrel movesdownward from the designed position thereof in the optical-axisdirection due to the curing shrinkage of the adhesive and the weight ofthe lens barrel.

By remarkably reducing the magnitude of such displacement, the focallength between a lens and an image sensor may be maintained very similarto the designed value thereof. Thereby, it is possible to achieve animprovement in the performance of the camera module, such as an increasein the resolution of an image of a subject to be photographed.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view illustrating a camera module according toone embodiment.

FIG. 2 is a bottom perspective view illustrating a lens barrel accordingto one embodiment.

FIG. 3 is a plan view illustrating the state in which the lens barrel isremoved from the camera module according to one embodiment.

FIG. 4 is a cross-sectional view illustrating a portion of the cameramodule according to one embodiment.

FIG. 5 is an enlarged view illustrating portion A of FIG. 4. FIG. 5illustrates one embodiment in the state in which an adhesive isinterposed and cured between the lens barrel and a lens holder in orderto attach the same to each other.

FIG. 6 is an enlarged view illustrating portion B of FIG. 5.

FIG. 7 is a perspective view illustrating a camera module according toanother embodiment.

FIG. 8 is a cross-sectional view illustrating the state in which a lensbarrel and a lens holder are coupled to each other according to anotherembodiment.

FIG. 9 is an enlarged view illustrating portion A1 of FIG. 8.

FIG. 10 is an enlarged view illustrating portion B1 of FIG. 9. FIG. 10illustrates the state in which the lens barrel and the lens holder areattached to each other using an adhesive containing no filler appliedthereto, unlike the embodiment.

FIG. 11 is an enlarged view illustrating portion B1 of FIG. 9. FIG. 11illustrates the state in which the lens barrel and the lens holder areattached to each other using an adhesive containing a filler appliedthereto according to the embodiment.

BEST MODE

Hereinafter, exemplary embodiments will be described in detail withreference to the accompanying drawings. While the exemplary embodimentsare susceptible to various modifications and alternative forms, specificembodiments thereof are shown by way of example in the drawings and willherein be described in detail. It should be understood, however, thatthere is no intent to limit the embodiments to the particular formsdisclosed, but on the contrary, the embodiments should be construed asincluding all modifications, equivalents, and alternatives fallingwithin the spirit and scope of the embodiments.

Although terms such as, for example, “first” and “second” may be used todescribe various elements, the components should be not limited by theseterms. These terms are merely used to distinguish the same or similarelements from each other. In addition, the terms particularly defined inconsideration of configurations and operations of the embodiments aremerely provided to describe the embodiments, and are not intended tolimit the scope of the embodiments.

In the description of the embodiments, when an element is referred to asbeing formed “on” or “under” another element, it can be directly “on” or“under” the other element or be indirectly formed with interveningelements therebetween. It will also be understood that “on” or “under”the element may be described relative to the drawings.

In addition, relative terms such as, for example, “on/upper/above” and“beneath/lower/below”, used in the following description may be used todistinguish any one substance or element with another substance orelement without requiring or containing any physical or logicalrelationship or sequence between these substances or elements.

In addition, in the drawings, the orthogonal coordinate system (x, y, z)may be used in the drawings. In the drawings, the x-axis and the y-axisindicate planes orthogonal to the optical axis, and for convenience, theoptical-axis direction (the z-axis) is referred to as a first direction,the x-axis is referred to as a second direction, and the y-axis isreferred to as a third direction.

FIG. 1 is a perspective view illustrating a camera module according toone embodiment. As illustrated in FIG. 1, the camera module according tothe embodiment may include a lens barrel 100, a lens holder 200, and anaccommodating unit 400.

The lens barrel 100 may include at least one lens 10, and may serve tocouple the lens 10 to the lens holder 200. The lens barrel 100 may becoupled to a through-hole formed in the lens holder 200 in various ways.

For example, a female screw-thread may be formed in the innercircumference of the through-hole in the lens holder 200, and a malescrew-thread may be formed in the outer circumference of the lens barrel100 so as to correspond to the female screw-thread in the lens holder200, whereby the lens barrel 100 may be coupled to the lens holder 200via screwing of these screw-threads.

However, the disclosure is not limited thereto, and as in the embodimentillustrated in FIG. 4 and the like, rather than forming thescrew-threads in the lens barrel 100 and the lens holder 200, the lensbarrel 100 and the lens holder 200 may be attached to each other usingan adhesive 20 (see FIG. 5).

Meanwhile, the lens 10 provided in the lens barrel 100, as illustratedin FIG. 4 and the like, may be configured with a lens sheet, and inanother embodiment, may be configured such that two or more lenses arealigned in an optical-axis direction, i.e. in the first direction so asto constitute an optical system.

The lens holder 200 is an area to which the lens barrel 100 is coupled,and may be formed in a central portion thereof with the through-hole toallow a portion of the lens barrel 100 to be inserted therein. Asdescribed above, the lens barrel 100 and the lens holder 200 may becoupled to each other via screwing, adhesion, or the like, and may alsobe coupled to each other using both screwing and adhesion.

The accommodating unit 400 may be coupled to the lens holder 200, andmay accommodate therein a printed circuit board, various elements, animage sensor (not illustrated) on which an image of a subject is formed,and the like. The lens holder 200 and the accommodating unit 400 may beintegrally formed with each other via injection molding or the like, ormay be separately manufactured and then coupled to each other viaadhesion, fusion, or fastener coupling, or the like.

FIG. 2 is a bottom perspective view illustrating the lens barrel 100according to one embodiment. The lens barrel 100 may include a firstadhesive portion 110. The first adhesive portion 110 is an area, thebottom surface of which faces the top surface of the lens holder 200,and which is attached to the lens holder 200.

Therefore, for convenience of description, the term “first adhesiveportion 110” refers to a lower portion of the lens barrel 100, to whichthe adhesive 20 is applied, and a portion adjacent thereto. Here, thefirst adhesive portion 110 may have a ring shape when viewed in thefirst direction, and may include a second recess 111, as illustrated inFIG. 2.

The ring shape described above and a ring shape to be described belowmay include not only a ring shape that is completely connected in asingle closed curve, but also a shape that approximates a ring shape,but is broken at a portion thereof. For example, any shape may appear asa ring shape so long as it approximates a ring shape overall becausebroken areas thereof are regularly distributed or because it hasconsistent bends, curvatures, or the like.

The second recess 111 may be formed inside the first adhesive portion110, and may have a ring shape when viewed in the first direction.Therefore, the first adhesive portion 110 is an area that includes thesecond recess 111 and the outer area thereof.

The second recess 111 may serve to prevent or remarkably reduce thegeneration of defects due to excessive deformation, breakage, and thelike in the process of manufacturing the lens barrel 100 and the firstadhesive portion 110.

In addition, when the lens barrel 100 and the lens holder 200 arecoupled to each other using the adhesive 20, the second recess 111 mayserve to provide a space in which a first protrusion 214 formed on thelens holder 200 may be disposed without interfering with the lens barrel100.

The second recess 111 may be formed by injection molding, or may beformed by cutting the area inside the first adhesive portion 110 using aprocessing tool. In particular, when the lens barrel 100 is formed of ametal material, formation by cutting using the processing tool may beeasier.

Meanwhile, a filter (not illustrated) may be coupled or disposed underthe lens barrel 100. The filter may be disposed under the lens barrel100 so as to face the lens 10 and to be spaced apart from the lens 10 inthe first direction.

The filter may serve to prevent light within a particular frequencyband, among light passing through the lens 10, from being incident on animage sensor (not illustrated), which is disposed under the filter so asto face the filter and to be spaced apart from the filter in the firstdirection. In one embodiment, the filter may be aninfrared-light-blocking filter.

That is, the light incident on the lens 10 passes through the lens 10and the filter and reaches the top surface of the image sensor such thatan image of a subject included in the incident light may be formed onthe top surface of the image sensor.

The filter may be coupled to the lens barrel 100 in one embodiment, asillustrated in FIG. 2, but may be disposed under the lens barrel 100 soas to face the lens barrel 100 and to be spaced apart from the lensbarrel 100 in the first direction.

FIG. 3 is a plan view illustrating the state in which the lens barrel100 is removed from the camera module according to one embodiment. FIG.4 is a cross-sectional view illustrating a portion of the camera moduleaccording to one embodiment.

The lens holder 200 may include a second adhesive portion 210. Thesecond adhesive portion 210 is an area, the top surface of which facesthe bottom surface of the lens barrel 100, and which is attached to thelens barrel 100.

That is, for convenience of description, the term “second adhesiveportion 210” refers to a portion of the top surface of the lens holder200 to which the adhesive 20 is applied and a portion adjacent thereto.Here, the second adhesive portion 210 may have a ring shape when viewedin the first direction.

As illustrated in FIGS. 3 and 4, the second adhesive portion 210 mayinclude a first recess 211, an outer surface 212, an inner surface 213,and the first protrusion 214. Here, as illustrated in FIG. 5, thedistance from the outer circumference of the second adhesive portion 210to the inner circumference 215 of the second adhesive portion 210 may bedefined as the width L of the second adhesive portion 210.

The first recess 211 may be formed between the outer surface 212 and theinner surface 213, and may have a ring shape in the circumferentialdirection of the second adhesive portion 210. At least some of theadhesive 20 may be applied to the first recess 211.

The first recess 211 may prevent the adhesive 20 from flowing down tothe outer circumference or the inner circumference 215 of the secondadhesive portion 210, and may serve to increase the adhesion surfacearea of the second adhesive portion 210, thereby increasing the couplingstrength of the lens barrel 100 and the lens holder 200 using theadhesive 20.

The outer surface 212 means the top surface of the second adhesiveportion 210 that is present outside the first recess 211, and the innersurface 213 means the top surface of the second adhesive portion 210that is present inside the first recess 211. Here, the adhesive 20 maybe applied to at least a portion of the inner surface 213 and the outersurface 212 so as to be attached to the bottom surface of the firstadhesive portion 110.

However, in order to prevent the adhesive 20 from flowing down to theouter circumference or the inner circumference 215 of the secondadhesive portion 210, it may be appropriate for the adhesive 20 to beapplied only to a portion of the outer circumference and the innercircumference 215 of the second adhesive portion 210.

The first protrusion 214 may protrude from the inner surface 213 in thefirst direction, and may be formed at a position spaced apart from thefirst indention 211. Here, the first protrusion 214 may be provided in aring shape along the circumferential direction of the second adhesiveportion 210.

The first protrusion 214 may serve to prevent the adhesive 20, appliedto the first adhesive portion 110 and the second adhesive portion 210,from overflowing to the inner circumference 215 of the second adhesiveportion 210. When the adhesive 20 overflows to the inner circumference215 of the second adhesive portion 210, a serious problem may occur.

For example, when the adhesive 20 overflows to the inner circumference215 of the second adhesive portion 210, and flows to the accommodatingunit 400 through a hollow region of the lens holder 200, the printedcircuit board, various elements, and the like provided in theaccommodating unit 400 may be contaminated, which may causedeterioration in performance and problems with operation thereof.

In particular, when the image sensor accommodated in the accommodatingunit 400 is contaminated by the adhesive 20, malfunction, breakage, orthe like of the image sensor may occur, which may cause seriousdeterioration in the quality of an image photographed by the cameramodule.

Therefore, in the embodiment, the first protrusion 214 may be providedto prevent the adhesive 20 from flowing to the lens holder 200 and theaccommodating unit 400 in order to prevent contamination of the printedcircuit board, various elements, and the image sensor provided in theaccommodating unit 400. Thereby, it is possible to prevent or remarkablyreduce deterioration in the performance of the camera module due to suchcontamination.

Meanwhile, the first protrusion 214 may be formed so as to be spacedapart from the inner circumference 215 of the second adhesive portion210 by a predetermined distance. When the lens barrel 100 and the lensholder 200 are coupled to each other, an active alignment process, i.e.a dynamic alignment process, may be performed.

In the active alignment process, the lens barrel 100 isthree-dimensionally moved along the x-axis, the y-axis, and the z-axisrelative to the lens holder 200, whereby the lens barrel 100 is alignedat an assembly position. In this procedure, the lens barrel 100 is movedin the first direction and/or in the second direction, i.e. in the x-yplane relative to the lens holder 200.

Therefore, in order to prevent the first protrusion 214 from hinderingthe movement of the lens barrel 100 when the lens barrel 100 is moved inthe x-y plane during the active alignment process, it may be appropriatefor the first protrusion 214 to be spaced apart from the innercircumference 215 of the second adhesive portion 210 by a predetermineddistance in the width direction of the second adhesive portion 210.

FIG. 5 is an enlarged view illustrating portion A of FIG. 4. FIG. 5illustrates one embodiment in the state in which the adhesive 20 isinterposed and cured between the lens barrel 100 and the lens holder 200in order to attach the same to each other. Here, the adhesive 20 may useepoxy, a thermosetting adhesive, or the like.

As illustrated in FIG. 5, when the adhesive 20 is cured, it may beappropriate for the position and the amount of application of theadhesive to be adjusted so that the adhesive is present on a portion ofthe bottom surface of the first adhesive portion 110, a portion of theouter surface 212 of the second adhesive portion 210, and a portion ofthe first recess 211 and the inner surface 213.

However, even when the adhesive 20 is applied at an incorrect position,or an excessive amount of the adhesive is applied, as described above,in particular, it is necessary to prevent the adhesive 20 fromoverflowing to the inner circumference 215 of the second adhesiveportion 210. As one method to prevent this, formation of the firstprotrusion 214 has been described above. Hereinafter, an additionalprevention method will be described.

As illustrated in FIG. 5, the second adhesive portion 210 may be formedsuch that the height of the outer surface 212 is lower than the heightof the inner surface 213. In this structure, even when the adhesive 20is applied at an incorrect position, or an excessive amount of adhesiveis applied, it is possible to prevent the adhesive 20 from overflowingto the inner circumference 215 of the second adhesive portion 210.

That is, since the adhesive 20 flows from the inner surface 213, whichis relatively high, to the outer surface 212 of the second adhesiveportion 210, even when the adhesive 20 is applied at an incorrectposition, or an excessive amount of the adhesive is applied, no adhesiveoverflows to the inner circumference 215 of the second adhesive portion210.

Accordingly, in the embodiment, since the second adhesive portion 210 isformed such that the height of the outer surface 212 is lower than theheight of the inner surface 213 in order to ensure that the adhesive 20flows from the inner surface 213 to the outer surface 212 of the secondadhesive portion 210, it is possible to prevent the adhesive 20 fromoverflowing to the inner circumference 215 of the second adhesiveportion 210.

The first recess is formed to have a curved cross section in FIG. 5, butthis is merely one given embodiment, and the first recess may be formedto have a polygonal cross section. In addition, a plurality of firstrecess may be formed in the width direction of the second adhesiveportion 210.

Meanwhile, the width of the first recess 211 may be about 80% of thethickness of a needle that is used to inject epoxy.

As described above, the second recess 111 may serve to provide the spacein which the first protrusion 214 formed on the lens holder 200 may bedisposed without interfering with the lens barrel 100 when the lensbarrel 100 and the lens holder 200 are coupled to each other by theadhesive 20.

Therefore, in order to allow the second recess 111 to provide the spacein which the first protrusion 214 is disposed, as illustrated in FIG. 5,it may be appropriate for the first protrusion 214 and the second recess111 to be provided so as to face each other in the first direction.

In order to allow the first protrusion 214 to prevent the adhesive 20from overflowing to the inner circumference 215 of the second adhesiveportion 210, the position at which the first protrusion 214 is disposedis important. Therefore, it may be appropriate for the first protrusion214 to be formed on the inner surface 213.

Specifically, it may be appropriate for the first protrusion 214, asillustrated in FIG. 5, to be formed on an inner area on the basis of theposition on the inner surface 213 that is half the width L of the secondadhesive portion 210.

The height of the first protrusion 214 may be related to the distancebetween the top surface of the image sensor and the upper end of thelens 10. That is, the width of the cured adhesive 20 in the firstdirection may be greater than the height of the first protrusion 214.

As the width of the adhesive 20 in the first direction increases, thepossibility of the adhesive 20 overflowing to the inner circumference215 of the second adhesive portion 210 increases, but the firstprotrusion 214 may prevent the adhesive from overflowing to the innercircumference 215.

When the width of the adhesive 20 in the first direction increases, thefocal length of the lens 10 may become different from the designed valuethereof, which may deteriorate the performance of the camera module.Therefore, it may be appropriate for the height of the first protrusion214, which corresponds to the maximum width of the adhesive 20 in thefirst direction, to be smaller than the tolerance corresponding to thedistance between the top surface of the image sensor and the upper endof the lens 10.

For example, when the tolerance corresponding to the distance betweenthe top surface of the image sensor and the upper end of the lens 10 isabout 300 μm, it may be appropriate for the height of the firstprotrusion 214 to range from 100 μm to 240 μm.

FIG. 6 is an enlarged view illustrating portion B of FIG. 5. A concreteembodiment related to the width w of the first recess 211 and the depthd of the first recess 211 will be described below with reference to FIG.6.

In order to increase the cross-sectional area over which the adhesive 20is applied and to ensure high coupling strength of the adhesive 20applied to the first recess 211, the width w of the first recess 211 maybe greater than the depth d of the first recess 211.

For example, as illustrated in FIG. 6, when the cross section of thefirst recess 211 has a curved shape, it may be appropriate for themaximum depth d of the first recess 211, i.e. the longest length of thefirst recess 211 measured in the first direction to be about half thewidth w of the first recess 211. In addition, a portion of the secondadhesive portion 210 described above may be additionally formed with anuneven structure.

However, this is merely one given embodiment, and it may be appropriatefor the ratio of the width w to the depth d of the first recess 211 tobe selected in consideration of the number and the cross-sectional shapeof first recess 211, the material and curing coupling strength of theadhesive 20, and the like.

FIG. 7 is a perspective view illustrating a camera module according toanother embodiment. As illustrated in FIG. 7, the camera moduleaccording to the embodiment may include a lens barrel 1000, a lensholder 2000, and an accommodating unit 4000.

The lens barrel 1000 may include at least one lens 20, and may serve tocouple the lens 20 to the lens holder 2000. The lens barrel 1000 may becoupled to a through-hole formed in the lens holder 2000 in variousways.

For example, a female screw-thread or a male screw-thread may be formedin the inner circumference of the through-hole in the lens holder 2000,and a male screw-thread or a female screw-thread may be formed in theouter circumference of the lens barrel 1000 so as to correspond to thefemale screw-thread or the male screw-thread in the lens holder 2000,whereby the lens barrel 1000 may be coupled to the lens holder 2000 viascrewing of these screw-threads.

However, the disclosure is not limited thereto, and rather than formingthe screw-threads in the lens barrel 1000 and the lens holder 2000, thelens barrel 1000 and the lens holder 2000 may be attached to each otherusing an adhesive 3000.

In addition, in another embodiment, the lens barrel 1000 and the lensholder 2000 may be coupled to each other using a method in which boththe above-described screwing and adhesion are combined. Hereinafter, thecase in which the combined method is used according to the embodimentwill be described.

The lens 20 provided in the lens barrel 1000, as illustrated in FIG. 8,may be configured with two or more lenses 20, which are aligned in theoptical-axis direction so as to constitute an optical system. In anotherembodiment, the lens 20 may be configured with a lens sheet.

The lens holder 2000 is an area to which the lens barrel 1000 iscoupled, and may be formed in a central portion thereof with thethrough-hole to allow a portion of the lens barrel 1000 to be insertedtherein. As described above, the lens barrel 1000 and the lens holder2000 may be coupled to each other via screwing, adhesion, a combinedmethod of screwing and adhesion, or the like. Hereinafter, in theembodiment, the case in which the combined method is used will bedescribed.

The accommodating unit 4000 may be coupled to the lens holder 2000, andmay accommodate therein a printed circuit board, various elements, animage sensor (not illustrated) on which an image of a subject is formed,and the like. The lens holder 2000 and the accommodating unit 4000 maybe integrally formed with each other via injection molding or the like,or may be separately manufactured and then coupled to each other viaadhesion, fusion, fastener coupling, or the like.

FIG. 8 is a cross-sectional view illustrating the state in which thelens barrel 1000 and the lens holder 2000 are coupled to each otheraccording to another embodiment. FIG. 9 is an enlarged view illustratingportion A1 of FIG. 8. In the embodiment, the lens barrel 1000 and thelens holder 2000 may be coupled to each other by a combined method ofscrewing and adhesion.

The lens barrel 1000 may have a first screw-thread 1100 as a malescrew-thread formed in a portion of the outer circumference thereof. Thelens holder 2000 may have a second screw-thread 2100 as a femalescrew-thread formed in the inner circumference of the through-hole.Since the first screw-thread 1100 and the second screw-thread 2100 arescrewed to each other, the shapes thereof may correspond to each otherso as to be suitable for screwing.

When the first screw-thread 1100 and the second screw-thread 2100 arescrewed to each other, a gap G may be formed. The gap G is a processingtolerance to ensure that the first screw-thread 1100 and the secondscrew-thread 2100 are smoothly screwed to each other.

That is, when the lens barrel 1000 and the lens holder 2000 are screwedto each other, one of the lens barrel 1000 or the lens holder 2000 isrotated to realize screwing between the first screw-thread 1100 and thesecond screw-thread 2100. At this time, when the first screw-thread 1100and the second screw-thread 2100 are processed so as not to form the gapG therebetween, rotation of the lens barrel 1000 or the lens holder 2000may be impossible or very difficult.

Therefore, by appropriately forming the gap G, it is possible to ensurethat the first screw-thread 1100 and the second screw-thread 2100 aresmoothly screwed to each other. Meanwhile, as illustrated in FIG. 11,the adhesive 3000 may be applied to the gap G in order to attach thefirst screw-thread 1100 and the second screw-thread 2100 to each other,thereby achieving stronger coupling of the lens barrel 1000 and the lensholder 2000.

FIG. 10 is an enlarged view illustrating portion B1 of FIG. 9. FIG. 10illustrates the state in which the lens barrel 1000 and the lens holder2000 are attached to each other using the adhesive 3000 containing nofiller applied thereto, unlike the embodiment.

With an adhesion method in which the adhesive 3000 containing no filleris applied to the surfaces of the first screw-thread 1100 and the secondscrew-thread 2100 so that the gap G is filled with the adhesive, asillustrated in FIG. 10, the lens barrel 1000 may move downward in theoptical-axis direction.

That is, the lens barrel 1000 may be disposed at a position movedfurther downward than the designed position thereof in the optical-axisdirection, and the reason therefor is as follows. After the adhesive3000 is applied to the surfaces of the first screw-thread 1100 and thesecond screw-thread 2100, the adhesive 3000 may undergo shrinkage due tocuring while the adhesive 3000 is cured.

Due to the shrinkage of the adhesive 3000, the thickness of the adhesive3000 disposed in the gap G may be reduced, and due to this, the width Lof the gap G filled with the adhesive 3000 may be reduced.

In addition, when the weight of the lens barrel 1000 acts before theadhesive 3000 is cured, as illustrated in FIG. 10, the width L of thegap G in the area in which the first screw-thread 1100 applies pressureto the second screw-thread 2100 due to the weight of the lens barrel1000 may be reduced, and the width L of the gap in the area in which thefirst screw-thread 1100 applies no pressure to the second screw-thread2100 may be increased.

Due to the above-described reason, that is, due to the curing shrinkageof the adhesive 3000 or the weight of the lens barrel 1000, the lensbarrel 1000 may be placed at a position moved further downward than thedesigned position thereof in the optical-axis direction when theadhesive 3000 disposed in the gap G is completely cured.

Such deviation of the lens barrel 1000 from the designed positionthereof may cause the following problem. An image sensor (notillustrated) may be provided under the lens 20 so as to face the lens 20and to be spaced apart from the lens in the optical-axis direction.

The focal length between the lens 20 and the image sensor is determineddepending on design specifications, and the distance between the lens 20and the image sensor is also determined depending on the focal length.

Therefore, when the lens barrel 1000 is disposed outside the designedposition, the distance between the lens 20 and the image sensor deviatesfrom the designed value thereof, and accordingly, the focal lengthbetween the lens 20 and the image sensor deviates from the designedvalue thereof.

When the focal length deviates from the designed value, the quality ofan image formed on the image sensor is deteriorated, and accordingly,needless to say, the quality of an image photographed by the cameramodule is also deteriorated.

Therefore, the focal length needs to fall within an allowable errorrange so as not to deviate from the designed value thereof. In theembodiment, it is possible to prevent the focal length from deviatingfrom the designed value by remarkably reducing the distance along whichthe lens barrel 1000 is moved downward in the optical-axis directionafter the adhesive 3000 is completely cured.

Hereinafter, according to the embodiment, a structure and a methodcapable of remarkably reducing the distance along which the lens barrel1000 is moved downward in the optical-axis direction due to the curingshrinkage of the adhesive 3000 or the weight of the lens barrel 1000will be described in detail with reference to FIG. 11.

FIG. 11 is an enlarged view illustrating portion B1 of FIG. 9. FIG. 11illustrates the state in which the lens barrel 1000 and the lens holder2000 are attached to each other using the adhesive 3000 containing afiller 3100 applied thereto according to the embodiment.

In the embodiment, the adhesive 3000, which is disposed in the gap Gbetween the first screw-thread 1100 and the second screw-thread 2100,may contain the filler 3100. Thus, the lens barrel 1000 and the lensholder 2000 may be attached to each other by the adhesive 3000containing the filler 3100.

Here, the adhesive 3000 may include, for example, a thermosettingadhesive 3000. In addition, the adhesive 3000 may be, for example, anepoxy material.

It may be appropriate for the filler 3100 to be formed of a materialthat has heat resistance so as not to melt at a certain hightemperature, in order to ensure that the filler 3100 exists in a solidstate at room temperature and may also exist in a solid state even whenit is heated for the curing of the adhesive 3000.

Therefore, it may be appropriate for the filler 3100 to be formed of,for example, at least one of SiO₂, CaCO₃, or Al(OH)₃. Here, needless tosay, the filler 3100 may use a mixture of the aforementioned materials.

The filler 3100 may have at least one of an irregular shape, a sphericalshape, or an ellipsoidal shape. Here, the term “ellipsoidal shape” meansa three-dimensional shape, of which a plane cut by the plane passingthrough the center has an elliptical shape. Here, needless to say, thefiller 3100 may have a shape that is a combination of the aforementionedshapes.

However, the use of the filler 3100 having a spherical shape or anellipsoidal shape may be more effective than the use of the filler 3100having an irregular shape. The reason therefor will be described belowin detail.

The filler 3100 may be contained in the adhesive 3000 to thereby beinserted, along with the adhesive 3000, into the gap G. When theadhesive 3000 is cured, the filler 3100 may remarkably reduce thedistance along which the lens barrel 1000 is moved downward in theoptical-axis direction due to the curing shrinkage of the adhesive 3000or the weight of the lens barrel 1000.

This is because the filler 3100 may serve to support the area in whichthe width L of the gap G is reduced due to the curing shrinkage of theadhesive 3000 or the weight of the lens barrel 1000, thereby preventingthe width L of the gap G from being greatly reduced.

That is, the filler 3100 may serve to restrict a displacement causedwhen the lens barrel 1000 is moved in the optical-axis direction due tothe curing shrinkage of the adhesive 3000 or the weight of the lensbarrel 1000 when the adhesive 3000 is cured.

Meanwhile, the lens barrel 1000 or the lens holder 2000 may be formed ofa non-metal material such as a plastic, but may be formed of a metalmaterial in consideration of durability or the like.

In the case of a non-metal material, when the lens barrel 1000 and thelens holder 2000 including the first screw-thread 1100 and the secondscrew-thread 2100 are manufactured via injection molding, the width L ofthe gap G may be accurately adjusted. Therefore, when the adhesive 3000is cured, the displacement of the lens barrel 1000 in the optical-axisdirection may be adjusted to fall within an error range that is allowedby design.

However, since a metal material is difficult to injection mold, thefirst screw-thread 1100 and the second screw-thread 2100 are formedusing a processing tool. Here, when the first screw-thread 1100 and thesecond screw-thread 2100 are successively and repeatedly formed, wear ofthe processing tool may occur.

Due to the wear of the processing tool, since it is difficult toaccurately adjust the width L of the gap G when the first screw-thread1100 and the second screw-thread 2100 are formed, it is difficult toadjust the displacement of the lens barrel 1000 in the optical-axisdirection so as to fall within an error range that is allowed by designwhen the adhesive 3000 is cured.

Therefore, in the embodiment, the use of the adhesive 3000 containingthe filler 3100 when the lens barrel 1000 and the lens holder 2000 areattached to each other is more effective in the case in which the lensbarrel 1000 or the lens holder 2000 is formed of a metal material.

The following Table 1 illustrates the suitability of assembly based onthe results of an experiment performed by changing the specifications ofthe filler 3100, that is, the longest length of the filler 3100, theshape of the filler 3100, and the mass ratio of the filler 3100 to theadhesive 3000. Here, the width L of the gap G is about 33 μm.

TABLE 1 Filler Specification Sample 1 Sample 2 Sample 3 Sample 4 Sample5 Sample 6 Longest 1.7 to 2.1 9 to 12 17 17 25 30 Length (μm) ShapeIrregular Irregular Irregular Irregular Spherical Spherical Shape ShapeShape Shape shape Shape Mass Ratio 20 45.1 30 15 15 15 (%) to Adhesive3000 Assembly Good Good Poor Poor Good Good

Here, the longest length of the filler 3100 may mean the longest lengthamong the measured lengths of the filler 3100 when the filler has anirregular shape, and may mean the diameter when the filler has aspherical shape. The longest length of the filler 3100 may be obtainedby irradiating each filler 3100 with light and measuring the scatteredform of the light incident on the filler 3100.

In addition, that assembly is good means that, when the lens barrel 1000or the lens holder 2000 is rotated so that the lens barrel 1000 isdisposed at the designed position thereof in the optical-axis direction,it is not necessary to change a torque, applied to the lens barrel 1000or the lens holder 2000 for assembly thereof, due to friction betweenthe filler 3100 and the surface of the first screw-thread 1100 or thesecond screw-thread 2100.

That is, it can be seen that assembly is good so long as a torque valuerequired for assembly is not excessively increased due to the frictionalforce generated between the filler 3100 and the first screw-thread 1100or the second screw-thread 2100.

Based on experimental results, since the fillers 3100 having thespecifications of Sample 3 and Sample 4 causes poor assembly, it may bemore appropriate to select the fillers 3100 having the specifications ofSample 1, Sample 2, Sample 5, and Sample 6.

The following Table 2 illustrates the results of an experiment in whichthe displacement of the lens barrel 1000 in the optical-axis directionwas measured after the adhesive 3000 was cured when using the fillers3100 having the specifications of Sample 1, Sample 2, and Sample 5.Here, since it is difficult to directly measure the displacement of thelens barrel 1000 in the optical-axis direction, a modulation transferfunction (MTF) value was measured.

The MTF value is a measured value of the contrast and the resolution ofthe lens 20, and is indicated as a ratio relative to a reference value.Thus, the MTF value is indicated as a dimensionless positive (+)numerical value, and the maximum value thereof is 1. In the embodiment,the greater MTF value means the greater displacement of the lens barrel1000 in the optical-axis direction. In the experimental results, the MTFvalue was measured multiple times, and the average value, the maximumvalue, and the minimum value thereof are illustrated.

TABLE 2 MTF Value Sample 1 Sample 2 Sample 3 Average Value 0.053 0.0500.039 Maximum Value 0.132 0.156 0.058 Minimum Value 0.018 0.012 0.011

Based on experimental results, it can be seen that the MTF value whenusing the filler 3100 having the specification of Sample 5 is smallerthan those in the cases of Sample 1 and Sample 2. That is, it can beseen that the displacement of the lens barrel 1000 in the optical-axisdirection after the adhesive 3000 is cured when using the filler 3100having the specification of Sample 5 is smaller than those in the casesof Sample 1 and Sample 2.

Meanwhile, since the longest length in the case of Sample 6 is greaterthan that in the case of Sample 5, although no experimental results areproposed, it is clearly expected that the MTF value when using thefiller 3100 having the specification of Sample 6 is smaller than thosein the cases of Sample 1 and Sample 2. That is, it can be appreciatedthat the displacement of the lens barrel 1000 in the optical-axisdirection after the adhesive 3000 is cured when using the filler 3100having the specification of Sample 6 is smaller than those in the casesof Sample 1 and Sample 2.

In consideration of the above-described experimental results, the rangewithin which assembly is good and the displacement of the lens barrel1000 in the optical-axis direction after the adhesive 3000 is cured isremarkably small is as follows.

First, the width L of the gap G may be set to a range from 18 μm to 48μm. More particularly, the width L of the gap G may be set to about 30μm.

It may be appropriate for the filler 3100 to have a spherical shape.Meanwhile, in the same manner as the spherical filler 3100, the filler3100 having an ellipsoidal shape may cause smaller frictional force withthe first screw-thread 1100 or the second screw-thread 2100, thusachieving good assembly, compared to a filler having an irregular shape.

In addition, it is clearly expected that the filler 3100 having anellipsoidal shape is similar in shape to the spherical filler 3100, andtherefore may exhibit characteristics similar to those of the sphericalfiller 3100. Accordingly, the filler 3100 having an ellipsoidal shapemay be appropriate.

In addition, it may be appropriate for the longest length of the filler3100 to be set to a range from 65% to 95% of the width L of the gap G.When the longest length of the filler 3100 is smaller than 65% of thewidth L of the gap G, the displacement of the lens barrel 1000 in theoptical-axis direction may be increased. When the longest length of thefiller 3100 is greater than 95% of the width L of the gap G, assemblymay become poor.

Here, when the filler 3100 has a spherical shape, it may be appropriatefor the diameter of the filler 3100 to be set to a range from 75% to 92%of the width L of the gap G.

In addition, it may be appropriate for the filler 3100 to be set to havea mass ratio within a range from 10% to 30% of the adhesive 3000. Moreparticularly, the filler 3100 may be set to have a mass ratio of 15% ofthat of the adhesive 3000.

In the embodiment, when the lens barrel 1000 and the lens holder 2000are attached to each other using the adhesive 3000 containing the filler3100, it is possible to remarkably reduce the magnitude of adisplacement by which the lens barrel 1000 is moved downward in theoptical-axis direction than the designed position thereof due to thecuring shrinkage of the adhesive 3000 or the weight of the lens barrel1000.

By remarkably reducing the magnitude of the displacement, the focallength between the lens 20 and the image sensor may be maintained verysimilar to the designed value thereof, and therefore, it is possible toachieve an improvement in the performance of the camera module, such asan increase in the resolution of an image of a subject to bephotographed.

Although several embodiments have been described above, various otherembodiments may be implemented. The technical ideas of the embodimentsdescribed above may be combined with each other in various forms so longas they are compatible, and new embodiments may be realized therefrom.

INDUSTRIAL APPLICABILITY

In the embodiments, by preventing an adhesive from flowing into a lensholder and an accommodating unit using a first protrusion, it ispossible to prevent contamination of a printed circuit board, variouselements, and an image sensor provided in the accommodating unit.Thereby, it is possible to prevent or remarkably reduce deterioration inthe performance of a camera module due to contamination. Thus, theembodiments have industrial applicability.

1. A camera module comprising; a lens barrel comprising at least onelens; and a lens holder coupled to the lens barrel, wherein the lensbarrel is formed with a first adhesive portion comprising a bottomsurface facing a top surface of the lens holder and attached to the lensholder, and the lens holder is formed with a second adhesive portioncomprising a top surface facing a bottom surface of the lens barrel andattached to the lens barrel, and wherein the second adhesive portion isformed with a first recess, to which at least a portion of an adhesiveis applied.
 2. The camera module according to claim 1, wherein thesecond adhesive portion has a ring shape when viewed in a firstdirection, and the first recess is formed in a ring shape in acircumferential direction of the second adhesive portion.
 3. The cameramodule according to claim 2, wherein a width of the first recess isgreater than a depth of the first recess.
 4. The camera module accordingto claim 3, wherein the depth of the first recess is half the width ofthe first recess.
 5. The camera module according to claim 2, wherein thesecond adhesive portion is formed such that a height of an outer surfacethereof that is present outside the first recess is lower than a heightof an inner surface thereof that is present inside the first recess. 6.The camera module according to claim 5, wherein the inner surface isformed with a first protrusion, and the first protrusion is spaced apartfrom the first recess in a direction orthogonal to the first directionand protrudes in the first direction.
 7. The camera module according toclaim 6, wherein the first adhesive portion has a ring shape when viewedin the first direction, and is formed in an inner area thereof with asecond recess having a ring shape when viewed in the first direction. 8.The camera module according to claim 7, wherein the first protrusion andthe second recess are provided so as to face each other in the firstdirection.
 9. The camera module according to claim 6, wherein the firstprotrusion is spaced apart from an inner circumference of the secondadhesive portion by a predetermined distance.
 10. The camera moduleaccording to claim 6, wherein the first protrusion is formed in an innerarea of the second adhesive portion at a position corresponding to halfa width of the second adhesive portion. 11-19. (canceled)
 20. A cameramodule comprising: a lens barrel comprising at least one lens; and alens holder coupled to the lens barrel, wherein the lens barrel isformed with a first adhesive portion comprising a bottom surface facinga top surface of the lens holder and attached to the lens holder, andthe lens holder is formed with a second adhesive portion comprising atop surface facing a bottom surface of the lens barrel and attached tothe lens barrel, and wherein the second adhesive portion is formedthereon with a first protrusion, and the first protrusion protrudes in afirst direction.
 21. The camera module according to claim 20, whereinthe second adhesive portion is formed with a first recess, to which atleast a portion of an adhesive is applied.
 22. The camera moduleaccording to claim 21, wherein the first adhesive portion has a ringshape when viewed in the first direction, and is formed in an inner areathereof with a second recess having a ring shape when viewed in thefirst direction.
 23. The camera module according to claim 22, whereinthe first protrusion and the second recess are provided so as to faceeach other in the first direction.
 24. The camera module according toclaim 21, wherein the second adhesive portion has a ring shape whenviewed in a first direction, and the first recess is foil led in a ringshape in a circumferential direction of the second adhesive portion. 25.The camera module according to claim 21, wherein a width of the firstrecess is greater than a depth of the first recess.
 26. The cameramodule according to claim 21, wherein the depth of the first recess ishalf the width of the first recess.
 27. The camera module according toclaim 20, wherein the second adhesive portion is formed such that aheight of an outer surface thereof that is present outside the firstrecess is lower than a height of an inner surface thereof that ispresent inside the first recess.
 28. The camera module according toclaim 20, wherein the first protrusion is spaced apart from an innercircumference of the second adhesive portion by a predetermineddistance.
 29. A camera module comprising; a lens barrel comprising atleast one lens; and a lens holder coupled to the lens barrel, whereinthe lens barrel is formed with a first adhesive portion comprising abottom surface facing a top surface of the lens holder and attached tothe lens holder, and the lens holder is formed with a second adhesiveportion comprising a top surface facing a bottom surface of the lensbarrel and attached to the lens barrel, wherein the first adhesiveportion has a ring shape when viewed in the first direction, and isformed in an inner area thereof with a second recess having a ring shapewhen viewed in the first direction, and wherein the second adhesiveportion is formed thereon with a first protrusion, and the firstprotrusion protrudes in a first direction.